Injection device

ABSTRACT

The invention relates to an injection device for injecting a selectable dose of a liquid substance from an ampoule ( 2 ), located in an ampoule holder ( 1 ), comprising a piston ( 12 ) and a sleeve-shaped mechanism holder ( 3 ), mechanically coupled thereto, in the interior of which a longitudinally shiftable shaft ( 4 ) is provided which acts on the ampoule ( 2 ), the shaft ( 4 ) being surrounded by an also longitudinally shiftable advancing sleeve ( 5 ), mechanically coupled thereto, which in its upper end area is closed by a lid ( 7 ). For selecting a dose of the liquid substance to be injected, a dosing sleeve ( 6 ) with a stepped member ( 13 ) is provided, which is disposed on the mechanism holder ( 3 ) in its upper end area, the dose to be respectively administered being adjustable by a rotation of the dosing sleeve ( 6 ) with the stepped member ( 13 ).

[0001] The invention relates to an injection device for injecting aselectable dose of a liquid substance from an ampoule located in anampoule holder, comprising a sleeve-shaped mechanism holder mechanicallycoupled thereto, in the interior of the mechanism holder alongitudinally shiftable shaft with a piston disposed thereon beingprovided which acts on the ampoule, wherein the shaft being surroundedby an also longitudinally shiftable advancing sleeve, mechanicallycoupled thereto, which in its upper end area is closed by a lid.

[0002] Such an injection device is known from EP 0 373 321 B 1 thatconsists of an ampoule sleeve for receiving the ampoule and a deliveringmechanism. In turn, this is composed of a cylindrical piston shaft withan inner hollow cylinder and an outer hollow cylinder which is formed inone piece with this and which exhibits a guiding cam on its outer shell.A dosing ring is fixed radially to the outer hollow cylinder. The dosingcan be read off by means of a scaling fastened to the outer perimeter ofthe dosing ring through a sight glass set into the housing of themechanism holder. The delivering mechanism is disposed longitudinallymovably in the mechanism holder by means of a retaining spring andsecured by a lid screwable into the housing of the mechanism holder. Thedosing ring rests against the lid with the force of the retainingspring. The housing of the mechanism holder is provided on its insidewith elongated slots of different length in which the correspondingguiding cam of the delivering mechanism is able to glide. As a result,the lift of the delivering mechanism is determined by the length of theelongated slot cooperating with the guiding cam. The adaptation of thedose to be administered to the needs of a patient takes placeexclusively by an authorized person, e.g. a physician. A special-purposewrench is necessary, by means of which an interlocking ring of thedevice can be unlocked until the guiding cam of the delivering mechanismis released from the respective elongated slot. The physician is thenable to select the desired dose by rotation of the released deliveringmechanism and renewed catch of the guiding cam into a correspondingelongated slot.

[0003] Once selected, the dose cannot be varied without considerableeffort. In addition, based on the construction of the deliveringmechanism, the injection device can only be used for delivering a singledose although possibly a sufficient supply of medicine is stillavailable in the ampoule. In order to administer another dose ofmedicine, the ampoule sleeve must be unlocked from the mechanism holderand disposed of together with the ampoule possibly still containingmedicine.

[0004] An injection device of generic type is known from EP 0 037 696 B1 with which a dose of a liquid substance to be administered can betaken from an ampoule via a transmission mechanism of tractive forceacting in one direction upon operating a locking cap. The transmissionmechanism of tractive force consists in that one pushing part isequipped with a plurality of teeth and the other pushing part with apawl, which intermesh and therefore effect the advance of thetransmission mechanism of tractive force only in one direction ofejection of the dose to be administered. The maximum lift height andtherefore the maximum dose to be administered is limited via a notch anda stop. The operator of the injection device is also able to select lessthan the maximum dose by listening to the number of clicks which occurwhen, during the advance, the teeth of the pushing part catch in thepawl. In this connection, one click corresponds to the minimum dose. Theoperating element, the locking cap, is pushed back up to a stop by meansof a spring.

[0005] This injection device is designed for extremely careful operationsince a click can easily be overheard and different doses to beadministered not be securely adjusted. In addition, no display unit isforeseen for the dose to be selected.

[0006] The present invention is therefore based on the problem toidentify an injection device of the type described above which is simplein the constructive design and simple in the handling and with which theoperator himself by simple movements is safely able to select the doseto be administered.

[0007] This problem is thereby solved in that a dosing sleeve with astepped member is provided for selecting a dose of a liquid substance tobe injected, which is disposed on the mechanism holder in its upper endarea, wherein the dose to be respectively administered being adjustableby a rotation of the dosing sleeve with the stepped member.

[0008] In this case, the dosing sleeve is composed of an operatingelement with a profile, an adjoining cylinder with dose imprint, a catchstop, and the stepped member adjoining this. The constructive couplingof the dosing sleeve to the injection device is thereby characterized inthat together with the stepped member and the cylinder with the doseimprint it surrounds the advancing sleeve.

[0009] The injection device according to the invention has thefundamental advantage that a dose, adjusted once, can be appliedrepeatedly; the user just has to load the injection device before eachinjection. The selection of the dose to be applied is quite easy due toa simple rotation of the dosing sleeve.

[0010] Further advantageous embodiments of the invention can be takenfrom the dependent claims.

[0011] One embodiment of the invention is represented in the figures.

[0012] It is shown in:

[0013]FIG. 1: the injection device according to the invention insection;

[0014]FIG. 2: the dosing sleeve with stepped member in a perspectiveview;

[0015]FIG. 3: a section along the line A-A in FIG. 1.

[0016] The injection device shown in FIG. 1 consists of the ampouleholder 1 in which the ampoule 2 with the piston 12 and with the liquidsubstance to be administered are located. The sleeve-shaped mechanismholder 3 is mechanically coupled to the ampoule holder 1 by a thread oranother suitable lock such as a bayonet lock. In the interior of themechanism holder 3, the longitudinally shiftable shaft 4 is disposedacting on the piston 12 of the ampoule 2. The shaft 4 is surrounded bythe also longitudinally shiftable advancing sleeve 5 mechanicallycoupled thereto, which is closed in its upper end area by the lid 7. Forselecting a dose of the liquid substance to be injected, the dosingsleeve 6 with the stepped member 13 is provided which is arranged on themechanism holder 3 in its upper end area. In this case, the dosingsleeve 6 with the stepped member 13 surrounds the advancing sleeve 5.The dose to be respectively adjusted and to be administered isselectable by a simple rotation of the dosing sleeve 6 with the steppedmember 13. The dosing sleeve 6 is mechanically coupled to the mechanismholder 3 via the catch stop 14. The dosing sleeve 6 consists, accordingto FIG. 2, of the profiled operating element 16, the adjoining cylinder15 with the dose imprint, the catch stop 14, and the stepped member 13adjoining this. The cam 8 is disposed on the advancing sleeve 5, whichupon withdrawing the advancing sleeve 5 in the direction of the lid 7comes to a stop against the step of the stepped member 13 respectivelyadjusted. Upon pressing down the advancing sleeve 5, the cam 8 comes toa stop against the shoulder 18 of the mechanism holder 3, resulting inthe injection lift X.

[0017] For mechanical coupling of shaft 4 with the advancing sleeve 5the shaft 4 is provided with the toothing 17 which cooperates with thelocking cam 10 of the advancing sleeve 5. In this case, the depth oftooth of the toothings 17 on the shaft 4 corresponds to the step heightof the stepped member 13. In the area of its lower end, the mechanismholder 3 comprises the catch 11 which also cooperates with the toothing17 of the shaft 4. The dose imprint on the cylinder 15 is visible via awindow 9 in the mechanism holder 3. In its interior, the mechanismholder 3 comprises a plurality of bulges 19 into which the projections20 of the stepped member 13 catch. (FIG. 3) The shaft 4 is non-rotatablylongitudinally shiftable.

[0018] The mode of operation of the injection device according to theinvention is as follows:

[0019] The operator turns the dosing sleeve 6 with the stepped member 13until the desired dose imprint on the cylinder appears in the window 9.Then, the injection device is loaded. FIG. 1 shows this before theloading. For the loading, the advancing sleeve 5 is pulled upward by thelid 7, mechanically coupled thereto, until the cam 8 which is part ofthe advancing sleeve 5 comes to a stop against the currently adjustedstep of the stepped member 13. In this case, the locking cam 10 of theadvancing sleeve 5 glides over the toothing 17 of the shaft 4, the teethof which (not shown) are arrow-shaped downward. In order to prevent thatthe shaft 4 is nevertheless shifted upward at the same time, the catch11 is provided on the mechanism holder 3 which is not shiftablelongitudinally. Thus, the catch 11 braces itself into the toothing 17and prevents motion of the shaft 4 upward. For administering theselected dose, pressure in the downward direction is exerted by theoperator on the lid 7 and on the advancing sleeve 5 coupled thereto. Inthis case, the locking cam 10 braces itself into the toothing 17 and, soto say, takes the shaft 4 along and the piston 12 coupled to the shaft 4exerts pressure on the ampoule 2 located in the ampoule holder 1, withwhich the liquid substance is applied by administering it through aninjection needle (not shown). Upon pressing down the advancing sleeve 5by means of the lid 7, the teeth of the toothing 17 also glide over thecatch 11 of the mechanism holder 3, wherein the catch 11 is out of meshby means of the selected arrow-shape of the teeth of the toothing 17.The advance motion of the advancing sleeve 5 in the downward directionlasts until the cam 8 comes to a stop against the shoulder 18 of themechanism holder 3 so that the selected dose of the liquid substance isadministered. The injection device is prepared by renewed loading forone or more subsequent injections. The shaft 4 remains during theloading processes in the immediately before-given state by means of thetoothing of catch 11 with the teeth of toothing 17. In particular, theshaft moves only in one direction, that is so to say downward, while theadvancing sleeve lets itself move in two directions, so to say upwardfor loading and downward for applying. The injection device according tothe invention can serve for the administering of medicine. However, itis also possible to administer lotions and other liquid substances withit.

[0020] The length of the injection lift X is determined by theindividual differences of the steps of the stepped member 13 such thatwith an ampoule 2 with a specific diameter X is an integral multitude ofa dose unit.

1. Injection device for injecting a selectable dose of a liquidsubstance from an ampoule (2), located in an ampoule holder (1),comprising a piston (12) and a sleeve-shaped mechanism holder (3),mechanically coupled thereto, in the interior of which a longitudinallyshiftable shaft (4) is provided which acts on the ampoule (2), the shaft(4) being surrounded by an also longitudinally shiftable advancingsleeve (5), mechanically coupled thereto, which in its upper end area isclosed by a lid (7), characterized in that, for selecting a dose of theliquid substance to be injected, a dosing sleeve (6) with a steppedmember (13) is provided which is disposed on the mechanism holder (3),in its upper end area, whereby the dose to be respectively administeredis adjustable by a rotation of the dosing sleeve (6) with the steppedmember (13).
 2. Injection device according to claim 1 , characterized inthat the dosing sleeve (6) with the stepped member (13) surrounds theadvancing sleeve (5).
 3. Injection device according to claim 1 or 2 ,characterized in that a cam (8), arranged on the advancing sleeve (5),comes to a stop upon pulling out the advancing sleeve (5) in thedirection of the lid (7) against the step of the stepped member (13),respectively adjusted, and upon pressing down the advancing sleeve (5),the cam (8) comes to a stop against a shoulder (18) of the mechanismholder (3), resulting in the injection lift X.
 4. Injection deviceaccording to one of the claims 1 to 3 , characterized in that, for themechanical coupling of the shaft (4) with the advancing sleeve (5), theshaft (4) is provided with a toothing (17) which cooperates with alocking cam (10) of the advancing sleeve (5).
 5. Injection deviceaccording to one of the claims 1 to 4 , characterized in that the depthof tooth of the toothings (17) on the shaft (4) corresponds to a stepheight of the stepped member (13).
 6. Injection device according to oneof the claims 1 to 5 , characterized in that, in the area of its lowerend, the mechanism holder (3) comprises a catch (11) which cooperateswith the toothing (17) of the shaft (4).
 7. Injection device accordingto one of the claims 1 to 6 , characterized in that the dosing sleeve(6) is composed of an operating element (16) having a profile, acylinder (15) with dose imprint adjoining thereto, a catch stop (14),and the stepped member (13) adjoining thereto.
 8. Injection deviceaccording to one of the claims 1 to 7 , characterized in that the doseimprint on the cylinder (15) is visible via a window (9) in themechanism holder (3).
 9. Injection device according to one of the claims1 to 8 , characterized in that, in its interior, the mechanism holder(3) comprises a multitude of bulges (19) into which the projections (20)of the stepped member (13) catch.
 10. Injection device according to oneof the claims 1 to 9 , characterized for the administering of medicines.